CS 182
Sections 103 - 104
Eva Mok (emok@icsi.berkeley.edu)
April 21, 2004
Announcements
• a9 out sometime Thursday, due Wednesday April
22nd, 11:59pm
• How’s your progress on the BBS articles?
Schedule
• Last Week
– SHRUTI
– Formal Grammar and Parsing
• This Week
– Construction Grammar, ECG
– Psychological model of sentence processing
• Next Week
– Language learning
– Learning ECG
Quiz
1. What is top-down parsing? Using a plausible CFG
grammar, what is the top down parse of “Pat ate
the kiwi”?
2. How well can CFGs represent English? What are
some mechanisms for improvement?
3. What are constructions?
4. What is the difference between subcasing and
evoking another schema or construction?
Quiz
1. What is top-down parsing? Using a plausible CFG
grammar, what is the top down parse of “Harry
likes the cafe”?
2. How well can CFGs represent English? What are
some mechanisms for improvement?
3. What are constructions?
4. What is the difference between subcasing and
evoking another schema or construction?
Grammar
• A grammar is a set of rules defining a formal language
• an example is right-regular grammar
• a more common example is Context-Free Grammar
β
•  : single non-terminal
• β : any combination of terminals and non-terminals
S  NP VP
NP  Det Noun | ProperNoun
VP  Verb NP | Verb PP
PP  Preposition NP
Noun  kiwi | orange | store
ProperNoun  Pat | I
Det  a | an | the
Verb  ate | went | shop
Preposition  to | at
Top Down Parsing: Pat ate the kiwi
• start from S and apply all applicable rules
• forward search (use your favorite search algorithm…)
S
NP VP
Det Noun VP
a Noun VP
a kiwi VP
an Noun VP
a orange VP
ProperNoun VP
the Noun VP
a store VP
S  NP VP
NP  Det Noun | ProperNoun
VP  Verb NP | Verb PP
PP  Preposition NP
Noun  kiwi | orange | store
ProperNoun  Pat | I
Det  a | an | the
Verb  ate | went | shop
Preposition  to | at
…
succeed when you encounter
Pat ate the kiwi
in a state without any non-terminals
(DFS)
Bottom Up Parsing: Pat ate the kiwi
• start from the sentence and try to match non-teriminals to it
• backward search (use your favorite search algorithm…)
S
S  NP VP
NP  Det Noun | ProperNoun
VP  Verb NP | Verb PP
PP  Preposition NP
Noun  kiwi | orange | store
ProperNoun  Pat | I
Det  a | an | the
Verb  ate | went | shop
Preposition  to | at
NP VP
NP Verb NP
NP Verb Det Noun
NP Verb Det kiwi
NP Verb the kiwi
NP ate the kiwi
ProperNoun ate the kiwi
Pat ate the kiwi
(DFS)
succeed when you encounter
S in a state by itself
Quiz
1. What is top-down parsing? Using a plausible CFG
grammar, what is the top down parse of “Harry
likes the cafe”?
2. How well can CFGs represent English? What are
some mechanisms for improvement?
3. What are constructions?
4. What is the difference between subcasing and
evoking another schema or construction?
Notice the ungrammatical and/or odd
sentences that we can generate?
S  NP VP
NP  Det Noun | ProperNoun
VP  Verb NP | Verb PP
PP  Preposition NP
•
*
Pat ate a orange
•
*
Pat shop at the store
•
*
Pat went a store
•
?
Pat ate a store
•
? The
Noun  kiwi | orange | store
ProperNoun  Pat | I
Det  a | an | the
Verb  ate | went | shop
Preposition  to | at
kiwi went to an orange
need to capture agreement,
subcategorization, etc
you could make many versions
of verbs, nouns, dets
 cumbersome
Unification Grammar
• Basic idea: capture these agreement features for each nonterminal in feature structures
• Enforce constraints on these features using unification rules
I
agreement
Went
agreement
number : SG
person : 1st
Pat
agreement
number : SG
person : 3rd
Shop
agreement
number :
person : 1st
VP  Verb NP
VP.agreement ↔ Verb.agreement
S  NP VP
NP.agreement ↔ VP.agreement
Quiz
1. What is top-down parsing? Using a plausible CFG
grammar, what is the top down parse of “Harry
likes the cafe”?
2. How well can CFGs represent English? What are
some mechanisms for improvement?
3. What are constructions?
4. What is the difference between subcasing and
evoking another schema or construction?
Embodied constructions
Form
Meaning
construction HARRY
form : /hEriy/
meaning : Harry
Harry
cafe
ECG Notation
CAFE
construction CAFE
form : /khaefej/
meaning : Cafe
Constructions have form and meaning poles that are subject to type constraints.
Quiz
1. What is top-down parsing? Using a plausible CFG
grammar, what is the top down parse of “Harry
likes the cafe”?
2. How well can CFGs represent English? What are
some mechanisms for improvement?
3. What are constructions?
4. What is the difference between subcasing and
evoking another schema or construction?
A schema hierarchy of objects (Nomi)
schema Entity
schema Place
schema Object
subcase of Entity
schema Referent
subcase of Entity
roles
category
distribution
boundedness
number
gender
accessibility
resolved-ref
schema Physical-Object
subcase of Object, Place
schema Animate
subcase of Physical-Object
roles
animacy
slot filler
constraints
animacy ← true
schema Manipulable-Object
subcase of Physical-Object
schema Cup
subcase of ManipulableObject
schema Human
subcase of Animate
roles
sex
schema Nomi
subcase of Human
sex ← female
schema Toy
subcase of
Manipulable-Object
schema Ball
subcase of Toy
The schemas we just defined
Entity
Referent
Place
Object
Physical-Object
Food
Cake
Manipulable-Object
Juice
Ball
Cup
Book
Animate
Toy
Block
Doll
Human
Bed
Nomi
Mother Father
A schema hierarchy of actions (Nomi)
schema Action
type constraint
roles
agent : Entity
schema DirectedAction
subcase of Action
roles
patient : Entity
schema Move
subcase of Action
roles
mover : Entity
direction : Place
schema CauseMove
subcase of DirectedAction, Move
roles
causer : Human
mover : Physical-Object
motion : Move
identification constraint
constraints
motion.mover ↔ mover
motion.agent ↔ causer
motion.direction ↔ direction
agent ↔ causer
patient ↔ mover
The schemas we just defined
Action
Directed Action
Move
Cause-Move
Transfer
JointMove
Constructions, finally (Nomi)
construction Ref-Expr
form : Schematic-Form
meaning : Referent
construction Nomi-Cn
level 0
subcase of Ref-Expr
form : Word
self.f.orth ← "Nomi"
local name
meaning
evokes Nomi as n
self.m.category ↔ n
self.m.resolved-ref ↔ n
fancy way of saying
that the category of
the referent is Nomi
construction Cup-Cn
level 0
subcase of Ref-Expr
form : Word
self.f.orth ← “cup"
meaning
evokes Cup as n
self.m.category ↔ n
self.m.resolved-ref ↔ n
Constructions, finally (Nomi)
construction Motion-Verb
meaning : Move
construction Cause-Motion-Verb
subcase of Motion-Verb
meaning : CauseMove
construction Get-Cn
level 0
subcase of Cause-Motion-Verb
form : Word
self.f.orth ← "get"
lexical
construction
Constructions, finally (Nomi)
construction Transitive-Cn
level 2
constructional
smaller constructions that it takes
constituents
agt : Ref-Expr
v : Cause-Motion-Verb
obj : Ref-Expr
ordering constraints on the constituents
form
agt.f before v.f
v.f before obj.f
meaning
v.m.agent ↔ agt.m.resolved-ref
v.m.patient ↔ obj.m.resolved-ref